Labels bearing information in any of a number of different optical code formats are commonly affixed to products, packaging, or other items and are used in many applications. It is common to encode retail product identification information in an optical code or bar code format on a product package or a label affixed to a product or package. Optical code symbols are also used on a broad range of retail packages for check-out and inventory purposes. A scanner, located at the check-out station of a retail establishment for example, is used to scan an optical code label to obtain product identification data for use by a host, such as an associated point-of-sale computer system.
In certain systems, multiple items are brought by the customer to the checkout counter, and the checkout clerk (or the customer) passes the item through the “read volume” of the scanner. The scanner reads the bar code and typically emits an audible tone indicating a successful read. The bar code data is then reported to the host.
Many retail checkout scanners include a fixed delay timer, which prevents multiple reporting of the bar code data. One such scanner is the Duet scanner, available from PSC Inc. of Eugene, Oreg. The fixed delay timer is activated when the scanner reads a bar code and reports the corresponding item data to the host. The timer is then restarted each time that the scanner reads the same bar code before the timer expires. When this occurs, data associated with the item is not reported to the host a second time. Thus, the item data is only reported multiple times if the timer expires before the bar code is read an additional time.
Many retail checkout scanners also include an integrated weigh scale for weighing certain items that are priced by weight (“weighable items”), such as produce. One such scanner is the Magellan®. scanner-scale, also available from PSC Inc. With the advent of bar codes or optical codes that are placed on food items and weighable items, a unique situation is created at the point of sale wherein the codes are contained within the scanner's read volume for an extended period of time. The extra time may be required while the items are being weighed and/or because the items may be placed within translucent bags which make reading more difficult. During this time, an optical code may be visible and then not visible to the scanner several times, due to movement of the items, movement of the semi-transparent bags containing the items, or other causes. Thus, even though it remains in the read volume, the optical code might be unreadable (or not visible) for longer than the timer delay. A similar situation may arise with smaller hard to read optical codes, such as those utilizing reduced space symbology (“RSS”). Because an RSS symbol in the form used on produce stickers is relatively difficult to read, it may be read once and then remain unreadable for longer than the timer delay, if an item is scanned slowly. In these situations, if the bar code subsequently becomes readable again, the scanner reports the additional read to the host. This reporting of the same item data multiple times is an unacceptable condition for the system.